Fuel battery system

Abstract

A fuel battery system comprises a fuel battery stack, a hydrogen supply system for supplying hydrogen from a hydrogen tank, an oxidant gas supply system for supplying air serving as an oxidant by an air compressor, an electrical system including an impedance measuring unit for measuring the impedance of a fuel battery, a DC/DC converter for converting generated electric power, a secondary battery for storing electric power, and so on, and a drive system for driving a vehicle. When the power generation is stopped by turning off an ignition switch in the state in which the power generation is suspended in an intermittent operation, the impedance measuring unit measures the impedance after the supply of air is stabilized to avoid the transient state of the fuel battery cell caused by a delay in air supply.

1. A fuel battery system comprising a fuel battery, a gas supplying device for supplying fuel gas and oxidant gas to the fuel battery, and an impedance measuring device for measuring impedance of the fuel battery, the fuel battery system comprising:
 an air compressor for supplying air which is the oxidant gas to the fuel battery; 
 a key switch for instructing a start or a stop to the fuel battery system; and 
 a controller for executing a film drying process based on an amount of water obtained by measurement of impedance when the key switch is switched OFF, wherein 
 the controller changes an operation mode of the fuel battery from a low output mode to a high output mode upon detecting that that the key switch is switched OFF, so as to avoid an excessive state of the fuel battery in an estimated start-up time of the air compressor caused by the change of the operation mode, and executes the impedance measurement after detecting that the supply of air has been stabilized. 
 
     
     
       2. The fuel battery system according to  claim 1 , wherein
 the controller detects that the supply of air has been stabilized by detecting that a predetermined time period from an increase of a rotational speed of the air compressor to a stabilization of the rotational speed of the air compressor has elapsed. 
 
     
     
       3. The fuel battery system according to  claim 1 , wherein
 the controller detects that the supply of air has been stabilized by detecting that a rotational speed of the air compressor has exceeded a predetermined rotational speed. 
 
     
     
       4. The fuel battery system according to  claim 1 , wherein
 the controller detects that the supply of air has been stabilized by detecting that a volume of air flow from the air compressor has exceeded a predetermined volume.